Re: (ET) charger - extension cords

[Ken Olum <kdo cosmos phy tufts edu>]

   From: "Bob Murcek" <rmurcek geisinger edu>
   Date: Wed, 30 Apr 2003 22:03:16 -0400

   By the way, cord coiling is a no-no when significant power, like
   that required for EV charging, is involved.  A coiled cord is an
   inductor, and that will increase voltage drop and heating.

I don't think so.  The current flows out through one wire in a cord
and back through the other, so there is no net current in the cord as
a whole.  Furthermore, induction would not cause heating.  In fact,
since the charger is a capacitative load, I think having an inductor
would improve the power factor and so reduce heating.

In my experience, the heating in the cord itself is trivial as
compared to the heating at the point where it is plugged in.  I think
the greatest value in having large wires is that they conduct heat
away from the plug where it is generated.

                       Ken